Syrian activists report 23 dead in Damascus suburb

Anti-regime activists say Syrian forces have killed at least 23 people in a restive suburb of the capital Damascus.

The Britain-based Syrian Observatory for Human Rights said 18 civilians were killed in an airstrike Tuesday on the city of Duma, northeast of Damascus. Five other rebel fighters were killed in clashes with regime forces nearby.

Syrian forces have stepped up their use of airpower against rebels seeking to topple President Bashar Assad as opposition fighters have made gains on the ground.

Activist say more than 35,000 people have been killed since Syria's troubles began in March, 2011.